2 Things

Riddle: The first thing always exists, and the second thing only exists when there's a lot of the first thing in one place. What are they?

Answer: Cars and traffic.

Source: https://www.riddles.com/index.php/9621

The first thing always exists, and the second thing only exists when there's a lot of the first thing in one place. What are they? — 2 things by Jack Albert v1.

Riddle: The first thing always exists, and the second thing only exists when there's a lot of the first thing in one place. What are they? Answer: Cars and traffic. — by Jack Albert v2.